This invention relates to the synthesis of bis(haloarylsulfonyl) aromatic compounds and more specifically, bis(chlorophenylsulfonyl) aromatic compounds. Bis(chlorophenylsulfonyl) aromatic compounds and particularly 4,4'-bis(4-chlorophenylsulfonyl)biphenyl are frequently used as monomers and comonomers in making high temperature polymers, and specifically polyarylene sulfide polymers which can possess glass transition temperatures greater than 260.degree. C.
Numerous studies have been conducted wherein the Friedel-Crafts sulfonylation reaction is used to synthesize sulfones by the reaction of an arylsulfonyl halide with an aromatic compound in the presence of a Lewis acid catalyst. Of particular interest in this application is the reaction of a halogen-bearing arylsulfonyl chloride with biphenyl. It is widely accepted by those skilled in the art that the presence of an election withdrawing functional group, such as halogen, on either the arylsulfonyl chloride or the aromatic reactant significantly reduces reactivity.
U.S. Pat. No. 4,303,776 teaches that a 45 percent yield of 4,4'-bis(4-chlorophenylsulfonyl)biphenyl is possible when biphenyl is contacted with a stoichiometric excess of 4-chlorobenzene sulfonyl chloride in the presence of a ferric chloride catalyst at a concentration of 0.20 moles catalyst per mole biphenyl reactant and a temperature of 140.degree. C. As the reaction proceeds, the mixture solidifies (see Control Test #1). When using a similar procedure, Cornell and Tajar ("A New Polyaryl Sulfone Thermoplastic Retaining Mechanical Properties up to 400.degree. F.," Society of Plastic Engineers, Tech. Paper 21, 621-3, 1973) report solidification of the mixture and a final yield of 65 percent 4,4'-bis(4-chlorophenylsulfonyl)biphenyl. Cornell et al. note the limitations of a solid final product on process operation and report that nitrobenzene at a concentration of 0.5 to 1.0 parts by weight per weight part biphenyl (0.625 to 1.25 mol/mol) is an excellent solvent for avoiding solidification and improves the yield of 4,4'-bis(4-chlorophenylsulfonyl)biphenyl to greater than 80 percent (see Control Test #2).
European Patent Application 0 351 954 teaches a process for preparing bis(halophenylsulfonyl) benzenoid compounds by reacting p-halosulfonyl halide with a benzonoid compound in an o-dichlorobenzene solvent at 110.degree. to 175.degree. C. and in the presence of ferric chloride catalyst. The resulting precipitant is tan to dark brown in color. The precipitant is then purified by refluxing the reaction mixture with either a hydroxy acid/water, hydroxy acid/alkanol, or a hydroxy acid/water/alkanol mixture at an elevated temperature thereby producing a bis(halophenylsulfonyl) benzenoid compound containing at least 70 ppm iron. The application teaches additional purification via a recrystallization process using an amide or amide/o-dichlorobenzene solvent.